Yellowstone National Park, Wyoming (CNN) -- Having spent an hour walking the trails in Yellowstone National Park, Erin Prophet suddenly heard the words that every hiker dreads.

"Bear! Twelve o'clock! He's heading towards you!" yelled a man paddling a kayak on the small lake behind her Friday.

Prophet, who lives in Boston, scanned the hill she had just begun to climb. She couldn't see anything, but then heard the thick brush in front of her begin to crackle.

A bear emerged from the forest. Prophet began slowly walking backwards. "I was pretty afraid," Prophet said. "Especially after what happened a couple of days ago."

"A couple of days ago" was Wednesday, when Brian Matayoshi, 57, and his wife Marylyn were hiking in a different part of the park and encountered a grizzly bear. The bear, a female with cubs, according to National Park Service rangers, charged the couple.

Brian Matayoshi was bitten and clawed by the bear repeatedly. Then the bear latched its mouth onto Marylyn Matayoshi's backpack, hoisting the woman up before throwing her onto to the ground. She lay still until the bear left.

By the time help arrived, Brian Matayoshi had died of his wounds. He was the first bear fatality in the park since 1986.

A ranger on the scene at the lake said he believed the bear to be a juvenile grizzly. But Ranger Kerry Gunther, who saw video footage of the bear, said he is certain it was a black bear. That species is smaller and typically less aggressive than grizzlies, but is known to occasionally attack humans.

Gunther, who has studied bears at Yellowstone for nearly 30 years, said the park usually has roughly 600 of both kinds of bears roaming its approximately 3,500 square miles. Typically, more than 3 million people will visit the park each year.

Despite the ample opportunity for humans to cross paths with bears, Gunther said there is usually only one bear-related injury each year. In the park's 140-year history, he said, six people are known to have been killed in bear attacks.

"Bears are really very tolerant of people," Gunther said. "I have had a few times where I was bluff charged but the bear always pulled up short. You don't really know if you are a 'runner' or a 'stander' until that happens."

Gunther said the park tries to keep visitors and bears a safe distance apart.

But more often than not it's the humans that don't follow that plan.

"We can have hundreds of visitors alongside the road filming and viewing bears," he said. "When the bears want to cross the roads you'd think to a big, 200 pounds-plus bear people would show a little bit more respect (and) get back to their cars or let the bear cross the road. Sometimes people are letting the bear walk just feet from them."

If a bear does show signs of aggression, Gunther said there are a series of steps people can take to survive the attack.

"That nanosecond before the bear hits you we recommend dropping to the ground and playing dead," he said. "Put your hands behind your neck so your elbows are protecting the sides of your face. Bears bite to the head and face a lot. By going passive usually they'll let you alone."

Gunther differentiates between defensive and predatory attacks by bears. If a bear shows signs of hunting and eating humans, Gunther said rangers will attempt to track down and euthanize the animal. But rangers don't typically kill a bear --like the grizzly that attacked the Matayoshis for defensive behavior.

That decision to let the bear live, Gunther said, has drawn both praise and criticism from the public. But, so far, Gunther said he is not aware of anyone canceling their stay at the park as a result of the mauling.

"People shouldn't fear bears," he said. "They should respect them." Respecting bears, Gunther said, means traveling in large hiking parties, leaving an area where bears are and carrying bear spray, a supersized can of pepper spray to ward off attacks.

As she watched the bear advance down the hill toward her, Prophet said she was all too aware that she was alone and had neglected to bring bear spray on her hike. She discarded the backpack she was carrying food in and retreated into the icy lake water while wondering what to do next.

"Grab on," said a voice behind her. The two men in the kayak who had first warned Prophet of the bear, now about 30 yards away from her, had reached the shore. Prophet grabbed onto the kayak as the two men pulled her through the water and away from the bear.

The bear appeared not to pay attention and took a quick swim around the lake before disappearing again into the woods.

Shaking from the cold lake water and adrenaline, Prophet was relieved to find herself on the far shore from the bear.

"There's a lot that runs through your head," she said. "What you've seen and heard about bear attacks. But I felt as long as I was not threatening him, he would go away."